The proposed project will continue development and improvement of the extensive medical knowledge base and diagnostic consultant programs originally known as INTERNIST-I. Specific subgoals of the project include translation of the INTERNIST-I knowledge base into a new format designed to overcome the representation limitations inherent in INTERNIST-I; production of an "electronic textbook" of medicine derived from the new knowledge base; refinement of a patient case simulator program which use the new knowledge representation to help train and evaluate medical students and house officers; and expansion and testing of a new diagnostic consultant program written by the principal investigator to correct known shortcomings of the INTERNIST-I diagnostic program. Computer program development will be done using Common Lisp on a Digital Equipment Corporation VAX and on Symbolics workstations to be provided by an associated R01 grant project.